1. Technical Field
This disclosure is directed to printed circuit boards (PCBs), and more particularly, to methodologies and structures for determining the registration between layers of a PCB.
2. Description of the Related Art
Modern PCBs typically include a number of different layers. A given PCB design may include at least one ground plane, at least one voltage plane, and at least one layer for conveying signals. Often times, PCBs will have multiple signal layers and in many cases, multiple instances of power and ground planes as well, particularly for those to be used in more complex systems.
In manufacturing PCB's having a number of layers, ensuring proper alignment between the layers (known as registration, or layer-layer registration) is an important factor to consider. During the various manufacturing processes, the layer-layer registration may become misaligned due to factors such as thermal expansion and contraction, among others. Accordingly, checking to ensure that the layer-layer registration is within a predetermined tolerance is important to ensure PCB quality. A wide variety of methods exists to determine layer-layer registration of PCBs.